Vulnerability · Published Feb 25, 2026 · Assigned by GitLab
CVE-2026-1388Inefficient Regular Expression Complexity in GitLab
High 7.5
In plain English
A high-severity regular-expression denial of service in GitLab from GitLab. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 64.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 9.2 before 18.7.5, 18.8 before 18.8.5, and 18.9 before 18.9.1 that could have allowed an unauthenticated user to cause regular expression denial of service by sending specially crafted input to a merge request endpoint under certain conditions.
Affected products (as reported)
Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- GitLab Issue #587560 issue-tracking, permissions-required
- HackerOne Bug Bounty Report #3482893 technical-description, exploit, permissions-required
- https://about.gitlab.com/releases/2026/02/25/patch-release-gitlab-18-9-1-released/